1. Field of the Invention
The present invention relates a leg for a piece of furniture.
2. Description of the Prior Art
Among others, describes SE B 442.581 a leg for a piece of furniture is known which for adjustment of the height of the table above the floor is provided with a telescopically movable portion which may be secured in the upper portion which is connected with the tabletop by means of a screw inserted in a threaded hole in the tube side on the upper portion of the leg. On account of the considerable impact on the lower portion from the screw, the lower portion has to be manufactured from a solid material, which makes the construction heavy. In order to make the threaded hole for the screw sufficiently strong, the tube wall around the threaded hole has to have a considerable thickness or be reinforced, for instance by a nut being welded on, which nut may subsequently be abraded for rounding of the corners, which is a laborious process making the whole construction more expensive. Where the tube wall in the upper portion has sufficient thickness for accommodating the threaded hole, the lower leg portion will have substantially smaller cross-section than the upper leg portion, which may be a drawback from an aesthetic point of view and it entails in any case a big material consumption for the upper leg portion and the whole construction becomes comparatively heavy.
Moreover, pieces of furniture are known, in which one of the legs is provided with a lower portion inserted in the upper leg portion by means of a thread, and by means of which the height of one of the legs may be adjusted in order to compensate for irregularities in the floor, or, if all the legs are provided with such a threaded portion, the height of the piece of furniture may be adjusted within a certain interval.
Moreover, a central column for a swivel chair is known, in which the parts are so to speak reversed, such that the tubular portion is placed in the base and the displaceable portion is extending upwards. The fastening device comprises a ring resting against the tubular portion and comprising a guide for the solidly designed, movable portion. The arrangement is based on the use of a screw pressing against the side of the displaceable portion and therefore suffers from the same drawbacks as the constructions discussed above.
It may be desirable in a piece of furniture to be able to change the length of all legs in order to change the height of the piece of furniture, and it will in this connection be desirable that the piece of furniture stands just as stable on the floor as before the adjustment. The adjustment is in other words to be carried out stepwise, and it should be simple to change the individual legs by the same number of steps. Moreover, there is a need for the adjustment interval to be big, for instance 25 cm, which corresponds to approx. 1/3 of the height of a leg. Furthermore, it is of importance that the adjustment may be incorporated in legs for pieces of furniture in which at least a part of the leg is manufactured from a seam-welded steel tube, and where the preparatory steps to be made to the tube are minimal and not damaging to a surface treatment previously made.
It is the object of the invention to provide a leg for a piece of furniture, which meets these requirements and in which such a stepwise adjustment may be made, such that a piece of furniture which has been levelled in advance retains its levelling after the height adjustment, and in which the leg for the piece of furniture is simple to adjust and stable in all settings.
It is also an object of the invention to design the fixing means in such a way that the leg for the piece of furniture on the outside appears with a surface without protrusions protruding substantially outside the surface of the upper leg portion.
These objects are met by a leg for a piece of furniture which is characterized by the subject matter of the characterizing clause of claim 1.
The lower leg portion is stably movable in the upper leg portion, because it substantially fills out the clear thereof, whereas the locking mechanism is placed in the longitudinal groove. Hereby, a construction is obtained, in which the difference between the cross-sections of the two portions is minimal, and in which the fixing means may be discreetly accommodated, as they do not have to protrude outside the hole in the tube wall, in which they are fastened, which is of considerable importance for the appearance of the piece of furniture.
When the adjustment of the height of the legs has taken place, it is advantageous that it is possible to obtain a locking of the height set. According to the invention a locking screw is placed in the protrusion, by means of which locking screw fixing means may be retained relative to the lower leg portion in the steps determined by the locking mechanism. In this embodiment no further changes have to be added to the upper leg portion, which thus preserves its smooth appearance.
In the simplest embodiment of the leg for the piece of furniture according to the invention the mechanism comprises a spring-loaded protrusion engaging a list provided with notches. By this embodiment the adjustment will take place stepwise, each step being marked by a click. When the desired height has been reached, the leg may be locked by additional fastening. This embodiment of the leg for the piece of furniture is well suited for legs for a piece of furniture, the cross-section of which deviates from the circular, as it is not required that the lower portion is rotatable with respect to the upper portion.
According to another embodiment of the leg for a piece of furniture according to the invention the lower leg portion can be rotated relative to the fixing means, and the longitudinal groove in its side wall has a row of recesses spaced by the same module, with which at least one protrusion on the fixing means may get into engagement and be disengaged by rotating of the lower leg portion in one direction or the other. This embodiment is advantageous in that a possible locking of the adjustment of the leg for the piece of furniture is not to transfer the load which is carried by the leg for the piece of furniture. This load is namely carried by the engagement between the protrusions and the recesses. The locking just has to prevent the two portions from being rotated relative to each other.
A special embodiment, in which the lower portion is only moved one step, each time it is rotated between one or the other of two positions, is characterized in that the longitudinal groove is provided with recesses along both sides, the fixing means having protrusions adapted to engage one or the other row of recesses, the recesses having such a distance from and such a width relative to the protrusions that the lower leg portion, when rotated to one of the sides, is movable over such a length that the disengaged protrusions may move one length corresponding to the module in the second row of recesses. In this embodiment there is no risk of the leg for the piece of furniture unintentionally sliding into its shortest position, if it is loaded during the adjustment.
In these embodiments an advantageous design of a securing against rotation, which at the same time conceals the locking means necessary for the height adjustment, may be characteristic in that the upper leg portion is surrounded by a movable cover skirt which is provided with an interior profiling which makes it substantially secured against rotation relative to the upper leg portion, said covering skirt engaging in its lowest position the lower leg portion and locking/securing it against rotation relative to the covering skirt. The covering skirt imparts a completely smooth appearance to the leg for the piece of furniture, the longitudinal groove being hidden, and at the same time an effective locking of the obtained adjustment is achieved. If the setting is to be adjusted, the skirt is lifted, whereby the lower leg portion is exposed so that it may be rotated and subsequently be adjusted as to height.
Another embodiment of the leg for a piece of furniture, and in which the circular cross-section of the upper leg portion is not a prerequisite, is characterized in that the longitudinal groove comprises a toothing along both side faces, which toothing does not extend through the whole depth of the groove, and in which a locking means, which at the side faces is provided with a corresponding toothing, is movable relative to the fixing means in a direction perpendicular to the longitudinal axis of the leg for the piece of furniture against a spring load in engagement with and in disengagement with the toothing in the longitudinal groove. By this embodiment the locking means may in one position be brought completely out of engagement with the toothing and in the other position act as an expander expanding the groove to such an extent that the lower portion, apart from not being longitudinally movable via the locking means relative to the upper leg portion, is also locked therein, which prevents any rocking movements.
A prerequisite for the most advantageous use of the leg for a piece of furniture according to the invention is that the piece of furniture is levelled relative to the floor, before the height-adjustment takes place. By doing so, it becomes possible to change the height-adjustment without losing the levelling. It is therefore preferred according to the invention to provide the base of the leg for the piece of furniture with an externally threaded tap, by means of which the base is connected with the lower leg portion, said threaded tap being longer than the distance between the steps of the locking mechanism.
Other advantageous embodiments appear from the remaining, dependent claims and from the following detailed description.